JPH06156252A - Method for molding bearing for piston rod of master cylinder - Google Patents

Abstract

PURPOSE:To provide a method for molding a synthetic resin bearing having annular inner and outer sealing grooves on inner and outer peripheral surfaces by using a simple structure molding die device having a non-split core die. CONSTITUTION:An insert ring 20, which corresponds to the shape of an inner seal and is easy to be broken and deformed, is attached to an integral core die 21, and side wall dies 22, 23 and an end wall die 24 form a cavity 25 by being closed. By filling the cavity 25 with a synthetic resin, a bearing 5 which envelopes the insert ring 20 is formed, and finally the insert ring 20 is removed while breaking and deforming it, and after that, an inner sealing groove 10 is produced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bearing mounted on a cylinder body for supporting a piston rod projecting from a rear end surface of a piston in a master cylinder for operating a brake, a clutch and the like of an automobile, and more particularly, an inner and outer circumference. The present invention relates to a method of forming a bearing having annular inner and outer seal grooves on its surface.

[0002]

2. Description of the Related Art A conventional piston rod bearing is made of metal, and a seal groove is formed on the outer peripheral surface of the bearing by cutting.

[0003]

Recently, as part of the weight reduction of the master cylinder, there is a demand for resinizing the above bearing.
However, if this entire bearing were to be obtained by a single injection molding of synthetic resin, the core mold had to be composed of a complicated split mold due to the existence of the inner seal groove, and the equipment cost was high. As a result, the cost of the bearing will increase.

The present invention has been made in view of the above points, and an object thereof is to provide a simple and effective method for molding the bearing with a synthetic resin without dividing the core mold.

[0005]

In order to achieve the above object, the present invention provides a step of mounting a rupturable or deformable insert ring corresponding to the shape of an inner seal groove on a core die, and A step of closing a pair of side wall molds that open and close in the radial direction and an end wall mold that opens and closes in the axial direction of the core mold to define a cavity around the insert ring; and filling the insert ring with a synthetic resin into the cavity. The method is characterized by including a step of forming the wrapped bearing and a step of removing the insert ring from the bearing while breaking or deforming the insert ring to expose the inner seal groove on the inner peripheral surface of the bearing.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

First, in FIG. 1, a master cylinder M for brake of an automobile is constructed in a tandem type in which a pair of front and rear pistons 2f and 2r are slidably fitted in a cylinder hole 1a of a cylinder body 1. The inside of the cylinder hole 1a is divided into independent hydraulic chambers 3f and 3r by both pistons 2f and 2r. When the rear piston 2r is moved forward, the hydraulic pressure generated in these hydraulic chambers 3f and 3r is applied to each wheel brake of the automobile (Fig. (Not shown).

On the rear end surface of the rear piston 2r, a piston rod 4 extending rearward from the cylinder body 1 is integrally projected, and a bearing 5 for slidably supporting the piston rod 4 is provided on the cylinder body. It is attached to 1.

That is, as clearly shown in FIG. 2, at the rear end of the cylinder body 1, from the rear end of the cylinder hole 1a to the bottom surface 6a.
Is formed into a bottomed hole-shaped bearing housing 6, and a synthetic resin bearing 5 having a stepped outer peripheral surface is fitted from the bearing housing 6 to the rear end of the cylinder hole 1a. Then, in order to prevent the retaining, the circlip 7 as a retaining ring is engaged with the annular retaining groove 8 on the inner peripheral surface of the bearing housing 6.

On the inner and outer peripheral surfaces of the bearing 5, annular inner and outer seal grooves 10 and 11 are provided, and the inner seal groove 1 is formed.
No. 0 is equipped with a cup seal 12 as an inner seal member for bringing the lip portion into close contact with the outer peripheral surface of the piston rod 4, and the outer seal groove 11 is provided with an outer seal member for contacting the inner peripheral surface of the bearing housing 6. The O-ring 13 is attached.

A circlip 7 is provided on the rear end surface of the bearing 5.
When the diameter is reduced so as to be released from the locking groove 8, an annular stopper wall 14 that restricts the diameter reduction limit is integrally provided.

Referring again to FIG. 1, the cylinder body 1 is connected to the shell 15 of the negative pressure booster B with a bolt 16 at a flange 1b provided at the rear portion thereof, and the output rod 17 is connected to the piston rod 4 in the shell 15. The rear piston 2r is driven forward by the thrust of the output rod 17.

Next, a method of molding the bearing 5 will be described with reference to FIG.

First, an insert ring 20 having a rectangular cross section corresponding to the shape of the inner seal groove 10 and capable of being relatively easily broken or deformed is prepared. Examples of the material of the insert ring 20 include thermoplastic resins such as polypropylene and nylon. After the insert ring 20 is prepared, it is attached to the integral core mold 21 as shown in FIG.

Next, as shown in FIG. 3B, the core mold 21
The pair of side wall molds 22 and 23 that are opened and closed in the radial direction and the end wall mold 24 that is opened and closed in the axial direction of the core mold 21 are closed.

Semi-annular projections 22a and 23a corresponding to both half peripheral portions of the outer seal groove 11 are formed on the inner surfaces of the side wall molds 22 and 23, respectively, and the side wall molds 22 and 23 and the end walls are formed. With the mold 24 and the core mold 21, the cavity 25 corresponding to the shape of the bearing 5 is inserted into the insert ring 2
Defined around 0. Therefore, a thermosetting synthetic resin such as phenol resin or epoxy resin is filled into the cavity 25 through a gate (not shown) to form the bearing 5 enclosing the insert ring 20.

When the bearing 5 is solidified, the side wall molds 22 and 23 and the end wall mold 24 are opened, and the bearing 5 is taken out together with the insert ring 20 from the core mold 21 as shown in FIG. 3 (c).

Then, as shown in FIG. 3D, when the insert ring 20 is removed from the bearing 5 while being broken or deformed, the inner seal groove 10 having a smooth inner surface without burrs appears thereafter.

Incidentally, it is necessary to apply a release agent to the outer surface of the insert ring 20 beforehand so that the insert ring 20 from the bearing 5 is
It is effective in easily and cleanly removing.

[0020]

As described above, according to the present invention, a step of mounting a rupturable or deformable insert ring corresponding to the shape of the inner seal groove on the core die and a pair of opening and closing in the radial direction of the core die. The step of closing the side wall mold and the end wall mold that opens and closes in the axial direction of the core mold to define a cavity around the insert ring, and filling the cavity with synthetic resin to form a bearing enclosing the insert ring. Since it has a step and a step of removing the insert ring from the bearing while breaking or deforming the insert ring to expose the inner seal groove on the inner peripheral surface of the bearing, an integral core type, a pair of side wall type and end wall type With the simple molding die device, the bearing made of synthetic resin having the inner and outer seal grooves can be easily molded, which can contribute to weight reduction and cost reduction of the bearing. Moreover, since the inner surface of the inner seal groove that appears after removing the insert ring can be made smooth without burrs, the sealing function of the inner seal member attached to the inner seal groove is not impaired.

[Brief description of drawings]

FIG. 1 is a vertical sectional side view of a master cylinder equipped with a bearing formed by the method of the present invention.

FIG. 2 is an enlarged view of part 2 of FIG.

FIG. 3 is a process drawing of forming the bearing.

[Explanation of symbols]

 1 Cylinder Body 4 Piston Rod 5 Bearing 10 Inner Seal Groove 11 Outer Seal Groove 20 Insert Ring 21 Core Type 22 Sidewall Type 23 Sidewall Type 24 Endwall Type 25 Cavity M Master Cylinder

Claims (1)

[Claims] 1. A master cylinder (M) is mounted on a cylinder body (1) for slidably supporting a piston rod (4), and annular inner and outer seal grooves (10,
A method for forming a piston rod bearing of a master cylinder, comprising: 11), wherein a rupturable or deformable insert ring (20) corresponding to the shape of an inner seal groove (10) is attached to a core mold (21). Process and a pair of side wall molds (2
2, 23) and the end wall mold (24) that opens and closes in the axial direction of the core mold (21) to define a cavity (25) around the insert ring (20), and A step of molding a bearing (5) encapsulating the insert ring (20) with a synthetic resin, and removing the insert ring (20) from the bearing (5) while breaking or deforming the inside of the bearing (5) And a step of exposing the inner seal groove (10) on the peripheral surface, the method for forming a piston rod bearing of a master cylinder.